Secondary sample dividers

The secondary sample dividers are used to reduce the size of the primary sample they can be classified5 as intermittent and reciprocating cutters, and continuous and rotational dividers. The rotational dividers are usually considered more suitable than linear cutters. 

Other designations for samples are bulk sample, primary sample, secondary sample, subsample, laboratory sample, and test sample. These terms are used when a sample of a bulk system is divided, possibly a number of times, before actually used in an analysis. For example, a water sample from a well... 

Other designations for samples are bulk sample, primary sample, secondary sample, subsample, laboratory sample, and test sample. These terms are used when a sample of a bulk system is divided, possibly a number of times, before actually being used in an analysis. For example, a water sample from a well may be collected in a large bottle (bulk sample or primary sample), from which a smaller sample is acquired by pouring into a vial to be taken into the laboratory (secondary sample, subsample, or laboratory sample), then poured into a beaker (another secondary sample or subsample), before a portion is finally carefully measured into a flask (test sample) and diluted to make the sample solution. 

It is very likely that the re-combined, primary sample taken from the whole is going to be too large for most powder tests and it, therefore, needs to be sub-divided into secondary or even tertiary sub-samples. This sub-division may be built into the primary sampling system or it may be achieved with a separate sample divider. Allen1 reviewed and tested most methods available for sample splitting and found the one based on the spinning riffler to be the best. 

The instrumentation for SSIMS can be divided into two parts (a) the primary ion source in which the primary ions are generated, transported, and focused towards the sample and (b) the mass analyzer in which sputtered secondary ions are extracted, mass separated, and detected. 

The SIMS process, as it relates to polymers, is characterized by three important parameters ion yield, transformation probability, and disappearance cross section. The ion yield (Y) is the ratio of the number of secondary ions produced divided by the number of primary ions incident on the sample Y = N(si)/N(pi). SIMS bombardment of a surface covered by a monolayer or less results in an exponential decay of the measured signal intensity 1(f) = I° exp[-(7(x)ypf/e] where is the primary ion current density, X the species measured, and cthe disappearance cross section. Thus <7 can be calculated from SIMS intensity decay curves. The disappearance cross section is the damage area caused by the primary ion which leads to desorption of a polymer molecule. 

The water in coal is bound in different forms to its constituents. It can be divided into three types (1) Free moisture, also referred to as external moisture, superficial moisture, or the primary moisture fraction, which is present in large cracks and capillaries. Water bound in this way retains its normal physical properties. (2) Inherent moisture, also referred to as internal moisture or the secondary moisture fraction, whose vapor pressure is lower, since it is absorbed within the pore structure of the coal. (3) Water of constitution, which is mainly combined with mineral matter normally present in coal. This water is generally driven off only at temperatures higher than those normally used for the determination of moisture content. Standard methods do not make use of these terms and define (1) the total moisture content of a coal and (2) the moisture content of the coal analysis sample. Total moisture determination must be made over the sample as received in the laboratory, in an air-proof recipient. The determination consists in drying in an oven at 105 °C till constant weight. Its value is of huge interest both in international and domestic coal trade (ISO 589, ASTM D3173). 

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